A total of 100 patients belonging to five families with the Nevoid Basal Cell Carcinoma (NBCC) Syndrome are to be studied for genetic analysis, cellular phenotype/cytogenetics and collaborative studies with molecular biologists in an attempt to isolate a geneable to transform NBCC cells from an abnormal phenotype to a normal phenotype. In the portion of this study designated "syndrome delineation" diagnostic radiology plays a significant role. Numerous skeletal abnormalities, visceral lesions (studied by abdominal and pelvic ultrasound) and dysplastic lesions in the brain (studied by CT scans) are noted. So far (May 1985) about twenty-five patients have been admitted to this protocol. Previously unrecognized skeletal changes in NBCC have been found in the patients studied to date. We have also documented a higher than usual incidence of gallstones in this group of patients as compared to the general population. Accrual of larger numbers of cases is awaited to make definitive statements.